Spectrophotometric Investigation of the Complexing Reaction between Rutin and Titanyloxalate Anion in 50% Ethanol |
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Authors: | Vesna Kuntić Dusěan Malesěev Zorica Radović Vladana Vukojević |
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Affiliation: | (1) Faculty of Pharmacy, University of Belgrade, YU-11001 Belgrade, Yugoslavia, YU;(2) Faculty of Physical Chemistry, University of Belgrade, YU-11001 Belgrade, Yugoslavia, YU |
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Abstract: | Summary. In the present work, rutin (3,3′ ,4′ ,5,7-pentahydrohyflavone-3-rhamnoglucoside) was determinated via a complexing reaction with a titanyloxalate anion. K2[TiO(C2O4)2] and rutin react in 50% ethanol forming a 1:2 complex in a pH range from 4.00 to 11.50, in which the TiO(C2O4)2 2− ion is linked to rutin through the 4-carbonyl and 5-hydroxyl group. The thermodynamic stability constant log β2 0 of the complex is determined to 10.80 at pH = 6.50. The change of the standard Gibbs free energy Δ G0 amounts to −61 kJċ mol−1, indicating that the process of complex formation is spontaneous. The optimal conditions for the spectrophotometric determination of microconcentrations of rutin are at pH=6.40 and λ= 430 nm, where the complex shows an absorption maximum with a molar absorption coefficient a 430=(60±2)ċ103 dm3ċ mol−1ċ cm−1. The method is applied rutin determination from tablets. Received January 4, 2000. Accepted (revised) February 17, 2000 |
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Keywords: | . Rutin Titanyloxalate anion Complexes UV/Vis spectroscopy. |
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